A weapon such as a rifle is typically aimed at long distances by use of a telescopic sight. Such a sight includes horizontal and vertical cross-hairs to provide aiming of the rifle toward the target. It is well known that if the target is located at greater distances from the rifle, the rifle angle above horizontal must be increased to compensate for the vertical drop by the projectile during its flight from the rifle to the target. There have been numerous techniques proposed for adjusting rifle elevation as a function of the distance to the target. Such techniques are shown, for example, in U.S. Pat. Nos. 42,983, 3,340,614, 3,92,450, 3,492,733, 3,588,250, 4,212,109, 4,263,719, and 4,403,421. However, these various techniques are not fully successful in providing rapid, accurate and automatic elevation compensation for the aiming of a rifle toward a target.
In view of the difficulty of providing range compensation for a rifle and the numerous problems involving prior mechanical methods, there exists a need for a nonmechanical, fast, accurate and reliable technique for providing range compensation.